#include <stdio.h>

int main() {
    int T,i,j;
    scanf("%d", &T);

    while(T--) {
        int N, K;
        scanf("%d %d", &N, &K);
        int A[8];

        for( i = 0; i < N; i++)
            scanf("%d", &A[i]);

        long long min_product = 1;

        for( i = 0; i < N; i++)
            min_product *= A[i];

        for( i = 0; i < N; i++) {
            long long product = 1;
            for( j = 0; j < N; j++) {
                if(i == j)
                    product *= (A[j] - K);
                else
                    product *= A[j];
            }
            if(product < min_product)
                min_product = product;
        }

        printf("%lld\n", min_product);
    }

    return 0;
}